Lindsay Lohan avoids Paris Hilton at Lady Gaga fragrance launch

Lindsay Lohan came face to face with old frenemy Paris Hilton and freaked out at a high-profile fashion bash, as their long-running feud continues to burn.

Lohan, who is working hard to put her troubled past behind her, arrived in New York from the Atlanta set of Scary Movie 5 in which she acts opposite Charlie Sheen and makes fun of her hard-partying, train-wreck past, including an incident last year when she was accused of stealing a necklace from an LA jewelry store.

But Lindsay wound up looking at [the Scary Movie cameo] as a way to complete a phase of her life and move on, a source said. After desperately trying to get out of the shoot, she filmed the role without any additional drama Wednesday.

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Lindsay Lohan

But when Lohan arrived at Lady Gagas masked ball Thursday night at the Guggenheim Museum, she flipped when she saw her old party-pal-turned-archrival Hilton.

Lindsay freaked out when she saw Paris, said a spy. Neither knew the other would be there. And when Lindsay first saw Paris, she just stepped back with these big eyes. She was shaking her head and kept repeating, No, no, I cant.

The once-tight pair had a falling out back in 2006 over the infamous incident when foul-mouthed oil heir Brandon Davis branded the Mean Girls star Firecrotch, with Hilton egging him on.

At the Gaga event, which launched the singers new fragrance, Fame, Lindsay refused to get her picture taken with Paris, a source said. But eventually she calmed down.

While Lohan arrived at the event very quietly, Hilton marched in and tried to push her way through the crowd to Gaga, only to turn around when she realized no one was moving out of her way when she wanted to get to the singer.

Lohan later received a hug f! rom Gaga, whom shed bonded with over the summer during a sleepover at the Chateau Marmont in LA.

Page Six exclusively reported that Gagas planning to cast Lohan in her first video from her upcoming album, Artpop.